Israel and Hamas agree a ceasefire after the worst flare up in violence in Gaza since the war in 2014
Police in Gaza is investigating the cause of a blast that killed a man and his son on Sunday.
"An explosion took place this morning in a house west of Gaza City," said police spokesman Ayman al-Batnijiy. He gave their ages as 35 and 13.
"The police launched an investigation into the cause of the explosion."
The blast came hours after Israel and Gaza's armed groups agreed on an Egyptian-brokered ceasefire on Saturday evening after a major escalation in cross-border violence.
But within hours both sides had once again fired at each other. Israel has carried out its biggest attack against Hamas militant targets in the Palestinian enclave since the war in 2014.
The Israel Defense Forces (IDF) said it had struck facilities used by Hamas including a battalion headquarters in Beit Lahia, a training camp and several weapons storage facilities.
Palestinian health officials said two teenagers were killed and 12 injured in an air strike in Gaza City.
The raids were a response to an onslaught of rockets fired into Israel. Around 100 of them are said to have been launched from Gaza.
Hamas has stopped short of claiming responsibility for the rocket fire but one official earlier called it a "deterrent to further Israeli attacks".
The cross-border violence comes amid rising tensions in recent months over Palestinian demands to reclaim ancestral homes in what is now Israel and a call for an end to the blockade of Gaza imposed by Israel and Egypt.